This invention relates to novel compositions of matter containing optically pure R(+) ondansetron. These novel compositions have potent antiemetic activity and are useful in ameliorating the nausea and vomiting otherwise induced by cancer chemotherapeutic agents and higher dose radiotherapeutic treatment procedures while avoiding adverse effects including but not limited to headache, constipation and increases in transeminase levels, which are associated with the administration of the racemic mixture of ondansetron. Additionally, these novel compositions of matter containing optically pure R(+) ondansetron are useful in treating behavioral disorders such as mood anxiety and schizophrenia, and such other conditions as may relate to R(+) ondansetron's activity as a competitive antagonist of serotonin receptor subtype 5-HT.sub.3, including but not limited to disorders of gastrointestinal motility, depression, migraine, alcohol, nicotine or drug (benzodiazepine et al.) withdrawal, while avoiding adverse effects associated with the administration of the racemic mixture of ondansetron. Furthermore, these novel compositions of matter containing optically pure R(+) ondansetron are useful in treating cognitive disorders such as dementia and age-associated memory impairment, while avoiding the adverse effects associated with the administration of the racemic mixture of ondansetron. Also disclosed are methods for treating the above described conditions in a human while avoiding the adverse effects that are associated with the racemic mixture of ondansetron, by administering the R(+) isomer of ondansetron to said human.
The active compound of this composition, and method is an optical isomer of the compound, ondansetron which is described in U.S. Pat. No. 4,695,578. Chemically, the active compound is the R(+) isomer of 1,2,3,9-tetrahydro-9-methyl-3-[(2-methyl-1H-imidazol-1-yl)methyl]-4H-carba zol-4-one. This isomer will hereinafter be referred to as R(+) ondansetron.